Divide the butter among four medium cast-iron skillets and place in the oven.
In a large blender, combine the eggs, milk, flour, 2 tablespoons of the vanilla and 1/4 cup of the sugar. Blend until smooth, 30 to 60 seconds.
Once the butter is melted and beginning to brown, carefully pull the skillets from the oven and evenly divide the batter among the skillets. Bake for 15 to 20 minutes, until bubbling and browned.
Meanwhile, place the blackberries, raspberries and strawberries in separate saucepans. Juice 1/2 lemon into each pan. Add 1/4 cup of the sugar and 1 tablespoon vanilla to each pan. Cook over medium heat, stirring, for 8 to 10 minutes. Make sure you watch the berries so they don't burn. If you like, use a spoon or spatula to crush the raspberries and blackberries to more of a paste.
Combine the cream, mascarpone, the remaining 1/4 cup sugar and 2 tablespoons vanilla in a stand mixer fitted with the whisk attachment. Whip for about 1 minute. Mix in food coloring until you reach the desired color.
To assemble: Place a Dutch baby on a serving plate and spread with the blackberries. Add a second Dutch baby and the raspberries. Repeat with a third Dutch baby and the strawberries. Top with the final Dutch baby (cooled so as not to melt the topping) and spread with the whipped topping. Garnish heavily with the rainbow sprinkles and dust with confectioners' sugar.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.